Condenser-Reboiler Vent Tubes for Non-Condensable Removal
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Solution Overview
Problem
Current condenser-reboiler systems in cryogenic air separation units face inefficiencies due to the accumulation of non-condensables like neon and helium, which increase resistance to heat transfer, require higher compression power, and complicate the recovery of valuable gases.
Innovation Solution
An improved tube and shell type condenser-reboiler system that uses an upward flow of nitrogen-rich vapor to condense and accumulate non-condensables at the top, allowing for their easy removal through vents, thereby enhancing thermal efficiency and reducing operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-condensables accumulate in the main condenser-reboiler, then heat transfer resistance increases, but thermal performance deteriorates
Solution Approach 1:
The condenser-reboiler is divided into multiple modules, each with its own perforated vent tubes. This segmentation allows localized removal of non-condensables from each module, preventing their accumulation and maintaining heat transfer efficiency across the entire system while reducing energy consumption.
Solution Approach 2:
Perforated vent tubes are installed to extract non-condensables (neon, helium) from the heat exchange surfaces. By actively removing these non-condensables through the vent tubes, the system maintains low heat transfer resistance and high thermal performance, preventing energy loss.
2Reliability
If non-condensables accumulate on heat transfer surfaces, then heat transfer resistance increases, but compression power requirements increase
Solution Approach 1:
The perforated vent tubes extract non-condensables from the heat exchange surfaces, preventing their accumulation. This maintains efficient heat transfer, which in turn maintains lower compression power requirements for the nitrogen vapor, as efficient heat transfer reduces the work needed for compression.
3Ease of operation
If non-condensables are dispersed throughout the condenser-reboiler, then removal becomes difficult, but recovery cost increases
Solution Approach 1:
Perforated vent tubes are strategically positioned to extract non-condensables directly from the heat exchange surfaces where they accumulate. This targeted extraction makes removal easy and efficient, and by concentrating the non-condensables in a manageable stream, it facilitates cost-effective recovery of valuable gases like neon.
Solution Approach 2:
The vent tubes are placed at specific locations where non-condensables naturally accumulate on heat transfer surfaces. This local placement optimizes the removal efficiency for each module, making the overall removal process easier and more cost-effective.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system improves thermal performance by separating and removing non-condensables, reducing energy consumption, and facilitating the recovery of high-value gases like neon, leading to lower operating costs and enhanced condensation heat transfer.
Implementation Method 1
uses an upward flow of nitrogen-rich vapor within the condenser-reboiler to condense the nitrogen-rich vapor and accumulate non-condensables at the top or upper region of the condenser-reboiler
Implementation Method 2
the heat exchange between the boiling liquid oxygen and the condensing nitrogen is carried out in a shell and tube heat exchanger
Implementation Method 3
the reboiling of the lower pressure column bottom liquid to provide reflux for the columns
Implementation Method 4
the nitrogen vapor is condensed, and at least some of the condensate is returned to the higher pressure column
Data Source
AI summary
A system and method for the concurrent condensation of a nitrogen-rich vapor and vaporization of an oxygen-rich liquid in a distillation column based air separation unit is provided. The disclosed system includes a condenser-reboiler heat exchanger located between a lower pressure column and a higher pressure column and configured to condense a nitrogen-rich vapor from the higher pressure column and partially vaporize an oxygen-rich liquid from the lower pressure column. Within the condenser-reboiler heat exchanger, the nitrogen-rich vapor flows in an upward direction such that any non-condensables present in the nitrogen-rich vapor will accumulate proximate the upper portion or top of the condenser-reboiler modules where they can be easily removed through venting by means of a venting apparatus having a plurality of perforated tubes.